1. Field of the Invention
The present invention relates to data storage devices for apparatus such as computers, and more particularly to a data storage device incorporating a spindle motor and having improved dynamic properties.
2. Description of Prior Art
Various data storage devices are installed in electronic apparatus for communication and handling of data. Such devices include, for example, hard disk drives, floppy disk drives and CD-ROM (Compact Disk-Read Only Memory) drives.
The trend toward portable applications for data storage devices has created the need for a new class of miniaturized data storage devices. Such data storage devices are being required to meet increasingly stringent physical and operating environment requirements. Small size and durability under harsh environmental conditions are characteristics that must co-exist in modern portable applications. Generally, conventional data storage devices cannot meet the above requirements. Referring to FIG. 3, a conventional data storage device comprises a stator 220, a rotor 240, a plurality of spaced, parallel disks 260 and a clamp 280. The stator 220 comprises a plurality of radial stator laminations 222. A winding 224 is wound around each stator lamination 222. The rotor 240 comprises a spindle shaft 242, and a hub 246 fixed to a top end of the shaft 242. The shaft 242 is fixed in a pair of bearings 244 seated in the stator 220. The rotor 240 is thus rotatably attached to the stator 220. A magnet 248 is attached to an inside of a bottom portion of the hub 246, the magnet 248 facing free ends of the stator laminations 222. The disks 260 are attached around the hub 246 by a clamp 280. The clamp 280 is fixed to the spindle shaft 242 by a screw 290. The clamp 280 comprises a resilient part 282 pressing a topmost disk 260. When the windings 224 are electrified, the magnet 248 is driven by the stator laminations 222, and the disks 260 of the rotor 240 rotate about the stator 220.
The above-described conventional data storage device comprises the hub 246 and a major portion of the stator 220 disposed at a same side of a baseplate of the stator 220. This necessarily requires a significant minimum height from the baseplate to a top of the hub 246. The height restricts the range of portable applications in which the data storage device can be used. In addition, the top end of the shaft 242 is located far from the baseplate, which results in instability of the bearings 244 and poor dynamic properties for the data storage device.